Mill to bear and Tight fit??

[aun]

I know that using tight fit at top flange and mill to bear at the bottom flange connection. what is the diferrence between these two order in Bridges construction??
TIA....

 

[Qshake]

Well,

One is simply a tight fit and the surface of such a stiffener or crossframe connection plate may be irregular so long as it is a tight fit.

Mill to bear, however, implies some action that is to be undertaken by the fabricator as well as structural action. The surface of this end must be milled and fabricated such as to transfer secondary stresses to the flange on a uniform surface with good contact at all points on the surface.

Obviously the latter is more expensive than the latter.